1. Field of the Invention
The present invention relates to a swing device such as a swing or a cradle and so on, and more particularly to an automatic swing device capable of automatically swing using electromagnetic force.
2. Description of the Prior Art
Generally, a swing device such as a swing or a cradle and so on moving front and back has been widely used in order for a good sleep or a play for a baby. Particularly, recently, an automatic swing device has been developed which automatically swings using an external power.
Such automatic swing device is classified into an electromotor type and an electromagnetic type in accordance with a driving manner thereof, wherein the electromotor type is swung in such a manner that a pivot of the cradle or swing is directly driven by a motor, and the electromagnetic type is swung in such a manner that the cradle or swing is driven with a repulsive force acting between a permanent magnet and an electromagnet.
The electromotor type swing device has a drawback in that an operational noise is generated and power consumption is large because it is driven by a motor.
Meanwhile, a conventional electromagnetic type swing device is provided in which a permanent magnet is disposed in a seat on which a baby is seated, an electromagnet is disposed at front and back sides in a pivot direction of the seat, and a photo sensor detects a pivot angle of the seat to selectively change a polarity of the electromagnet, whereby the seat is swung front and back by a repulsive force acting between the permanent magnet and the electromagnet.
That is, when the permanent magnet approaches the electromagnet, the polarity of the electromagnet is changed into the same one as that of the permanent magnet to provide repulsive force between the permanent magnet and the electromagnet, so that the seat is swing in opposite direction by the repulsive force.
However, such electromagnetic type swing device has problems in that a structure is complicated and in that, if the photo sensor detects a wrong position of the seat, the polarity of the electromagnet is changed opposite to that of the permanent magnet so that a malfunction is possibly generated in which the seat is fixed on that position.